Index: source/lib/sysdep/arch/x86_x64/topology.cpp
===================================================================
--- source/lib/sysdep/arch/x86_x64/topology.cpp
+++ source/lib/sysdep/arch/x86_x64/topology.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2020 Wildfire Games.
+/* Copyright (C) 2021 Wildfire Games.
  *
  * Permission is hereby granted, free of charge, to any person obtaining
  * a copy of this software and associated documentation files (the
@@ -101,6 +101,18 @@
 			DEBUG_WARN_ERR(ERR::CPU_FEATURE_MISSING);
 		const size_t logicalPerPackage = bits(regs.ebx, 16, 23);
 		const size_t maxCoresPerPackage = MaxCoresPerPackage();
+
+#if defined(CPUID_IMPLEMENTATION_PIC86)
+		// first generation Intel multi-core systems without HT (Penryn,
+		// Wolfdale, Yorkfield) falsely set the HT bit
+		// its confused inline asm in x86_x64::__cpuid() for GCC+i386+PIC
+		// hide assert and disable hyperthreading
+		if(logicalPerPackage % maxCoresPerPackage && x86_x64::Vendor() == x86_x64::VENDOR_INTEL && x86_x64::Family() == 6)
+		{
+
+			return 1;
+		}
+#endif
 		// cores ought to be uniform WRT # logical processors
 		ENSURE(logicalPerPackage % maxCoresPerPackage == 0);
 		const size_t maxLogicalPerCore = logicalPerPackage / maxCoresPerPackage;
Index: source/lib/sysdep/arch/x86_x64/x86_x64.h
===================================================================
--- source/lib/sysdep/arch/x86_x64/x86_x64.h
+++ source/lib/sysdep/arch/x86_x64/x86_x64.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2010 Wildfire Games.
+/* Copyright (C) 2021 Wildfire Games.
  *
  * Permission is hereby granted, free of charge, to any person obtaining
  * a copy of this software and associated documentation files (the
@@ -37,6 +37,19 @@
 #include <intrin.h>	// __rdtsc
 #endif
 
+#if defined(_MSC_FULL_VER) && _MSC_FULL_VER >= 150030729
+// VC10+ and VC9 SP1: __cpuidex is already available
+# define CPUID_IMPLEMENTATION_WINDOWS
+#elif GCC_VERSION
+# if defined(__i386__) && defined(__PIC__)
+#  define CPUID_IMPLEMENTATION_PIC86
+# else
+#  define CPUID_IMPLEMENTATION_UNIX
+# endif
+#else
+# error "compiler not supported"
+#endif
+
 namespace x86_x64 {
 
 /**
Index: source/lib/sysdep/arch/x86_x64/x86_x64.cpp
===================================================================
--- source/lib/sysdep/arch/x86_x64/x86_x64.cpp
+++ source/lib/sysdep/arch/x86_x64/x86_x64.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2018 Wildfire Games.
+/* Copyright (C) 2021 Wildfire Games.
  *
  * Permission is hereby granted, free of charge, to any person obtaining
  * a copy of this software and associated documentation files (the
@@ -46,23 +46,21 @@
 
 namespace x86_x64 {
 
-#if defined(_MSC_FULL_VER) && _MSC_FULL_VER >= 150030729
+#if defined(CPUID_IMPLEMENTATION_WINDOWS)
 // VC10+ and VC9 SP1: __cpuidex is already available
-#elif GCC_VERSION
-# if defined(__i386__) && defined(__PIC__)
-#  define __cpuidex(regsArray, level, index)\
+#elif defined(CPUID_IMPLEMENTATION_PIC86)
+# define __cpuidex(regsArray, level, index)\
 	__asm__ __volatile__ ("pushl %%ebx\n"\
 		"cpuid\n"\
 		"mov %%ebx,%1\n"\
 		"popl %%ebx"\
 		: "=a" ((regsArray)[0]), "=r" ((regsArray)[1]), "=c" ((regsArray)[2]), "=d" ((regsArray)[3])\
 		: "0" (level), "2" (index));
-# else
-#  define __cpuidex(regsArray, level, index)\
+#elif defined(CPUID_IMPLEMENTATION_UNIX)
+# define __cpuidex(regsArray, level, index)\
 	__asm__ __volatile__ ("cpuid"\
 		: "=a" ((regsArray)[0]), "=b" ((regsArray)[1]), "=c" ((regsArray)[2]), "=d" ((regsArray)[3])\
 		: "0" (level), "2" (index));
-# endif
 #else
 # error "compiler not supported"
 #endif